Mud anchor



April '14, 1959 J. R. REEVE 2,

7 I MUD ANCHOR Filed Maich 12, 1956 I 4 Sheets-Sheet 2 INV ENTOI: BYJOHNRUMSEY- REEVE A rTYf United States Patent MUD ANCHOR John Rumsey Reeve,Tulsa, Okla.

Application March 12, 1956, Serial No. 570,850 2 Claims. (Cl. 61-465)This invention relates to mud anchors and floating foundations for usein oflshore drilling. Drilling for oil, gas, or sulphur in the water ofthe outer continental shelf is limited by the depth of the water.Platforms built on piling for drilling wells, or barges raised oncaissons or piling are extremely diificult and expensive to constructand maintain in water morethan 75 to 100 feet deep because the soft mudof the sea bottom is not stable enough to support the heavy structuresby the use of ordinary piling. So it is an object of this invention todevise a special type of floating structure from which drilling can becarried out and yet which structure while floating is stabilized onpiling that is anchored. More particularly, this invention proposes acatenarily anchored deck for supporting the drilling equipment whichdeck has an open cylinder fixedly depending from each corner portionthereof and an enclosed entirely submerged decksupporting float for eachcylinder vertically through which float the cylinder fixedly rises toand through the deck, while piling rises through each cylinder from thesea bottom. The floats are submerged so as not to be affected by surfacewave action and the deck is supported therefrom, so. it is a furtherobject of this invention to devise ways and means for stabilizingtheelevation of the floating deck with respect to the piling that risesupwardly from the sea bottom, and another object is to associate thefloating but anchored deck with the fixed piling rising through itscorners, under conditions whereby the piling is maintained under tensionrather than compression, while a further object is to devise means forregulating that tension. Yet another object of the invention is todevise means whereby the deck is automatically restored to its normalposition if and when the deck tends to settle. A further object is toprovide stop means for limiting further settling of the deck in theevent that the automatic means for some reasondoes not actually restorethe settling deck to its norm.

In order to accomplish the foregoing objects, the deck while floatingmust be anchored, so it is an object of this invention to devise a newand effective mud anchor that is useful not only for this deck, andfor-its pilings, but is also useful in supporting or anchoring varioustypes of marine structures.

These, and possibly other, objects can be realized by a floating butanchored deck having an open cylinder fixedly depending from each cornerportion thereof, an enclosed entirely submerged deck-supporting floatfor each cylinder vertically through which float the cylinder fixedlyrises toand through the deck while the floats are secured inhorizontally-spaced relationship with anchored piling rising througheach cylinder from the sea bottom.

The deck is catenarily anchored and has means for controlling the depthof submergence of each float as well as means for applying regulatedtension on each piling. This last sentence described in broad languagepoints to features of novelty of this invention but many of suchfeatures are also included in the construction and arrangement of eachof the three means mentioned, including Patented Apr. 14, 1959 "ice alsothe details of the mud anchor together with the manner of itsemplacement, as shown and described herein.-

of an anchor head with the pipe extension by the use of which the anchoris emplanted. Fig. 3 is an isometric view with parts in section of theanchor head. Fig. 4'

is a vertical sectional view through a portion of the' pipe extensionshown in Fig. 2. Fig. 5 shows a transverse view looking down on theanchor head, taken along the line 5-5 in Fig. 3. Fig. 6 is a plan viewof one of the blades or discs of the anchor head. Fig. 7 is a sideelevational view of the floating structure except for its derrick or rigW, while Fig. 8 is a plan view thereof. Fig. 9 is a partial isometricview with parts in section of one of the floats 51 and its connections.Fig. 10 is a vertical sectional view through one of the service tubes62, and its connections. Fig. 11 is a partial isometric view of theleveroperated switch mechanism L. Fig. 12 is a vertical sectional viewthrough a piling and one of the casing rings and slip S.

Since the floating platform or deck of this invention as well as thepiling thereof must be anchored, there will be described first a form ofanchor head that I prefer to use,

although it is not indispensable to the invention, and indeed, it hasother uses without being associated with embodiments of the floatingdeck invention. So the head H has a pointed end 11 carried by a tubularbody 12, provided with a set or plurality of superposed peripheral slotsalternately numbered 13 and 14 whose extent is approximately a alignedparallelly.--

semicircumference, and which are slots 13, is a shaft 15 rockably heldin lugs 16 extending inwardly from the periphery of the tubular body 12,and

secured to this shaft to rock therewith, are a set or plurality of discsor blades 17, with each disc aligned with one of the slots 13, so thatas the shaft15 is rockably rotated, ts discs each swing as agroupthrough a slot,13 with which it is aligned whereby the discs 17then extend laterally from one side of the tubular body 12, as shown"in- Figs. 2 and 5. In the tubular body there is anotherrockable shaft18, similar in all respects to shaft'15,"ex.-

cept located at therefrom, rockably supported'in lugs 19, and havingsecured to the shaft, another set of discsv or blades 20, aligned withslots 14, whereby they" can swingingly pass through those slots toextend laterally from the tubular body 12, but on a diflerent axis thando the discs 17 and in a different direction therefrom. These discs areall similarly shaped. and are generally circular in plan view but as canbe seen in Fig;

6, wherein approximately three-quarters of the disc is circular, but itsfourth quarter Q has its periphery given a sharper curvature ortumblehome at 22 tov provide av shoulder 23 adjacent the rockable shaft15 from which the disc is supported. If the discs were fully circular,in 1 order to get them to swing through their associated slots,-

the slots would have to extend through more than onehalf thecircumference of the tubular body (because otherwise the discs would bestopped by the limitation of the slots) and this would weaken that bodytoo much,

so by providing the tumblehome 22, andv the shoulder 23, a

a shorter slot thus can be used. For the purpose of emplacing the mudanchor of anchoring head H, it can have section of pipe 28 reaches to anelevation above the Extending longitudinally I and in-'* ternally of thetubular body 12 adjacent one end of the wotet level upto a barge29 orother float from which 2 workmen can operate. In this extending pipingthere rises through lugs 31 extensions such as 32, 33 and 34, ofrockable shaft 15 in the tubular head 12, and these are coupled togetherby couplings such as 35, but the bottom coupling:35" is splined so thatthe shaft extension can be uncoupled thereat. In the same manner,rockable shaft 18 in thetubular head 12, has shaft extensions 36, 37 and38,- rotatable in lugs 39, and having couplings such as 40, but; thebottom coupling 40 is splined so that the shaft extensions can beuncoupled thereat. At the top of shaft extensions '34 and 38, at anelevation above the waterlevel, are meshing gears 41 and 42, that may bemotivated by a suitable motor and speed reducer 43 (supported on a bargeB), adapted for rotating the shaft extensions 34 and 38,-. andthusrocking the disc-bearing shafts 15 and 18in the tubular body of theanchor, to swing the discs orblades 17 and 20 through the slots withwhich they arealigned toproject them into the mud M of the bottomtoprovide laterally extending anchoring surfaces for resisting pull on theanchor head. As soon as the discs or blades have been so laterallyprojected by the rocking of the shafts that carry them motivated fromthe motor temporarily located on the top of piling or other suchsupport, the .shaft extensions 34 and 38, with their splinecl couplingssuch as 35' and 40' can be removed from shafts 15 and 18 of the tubularanchor head and drawn up to the surface. Thereafter, the pipe extensionssuch as 25, 27 and 28 with their weldings can be unscrewed from theanchor head and drawn up to the surface, leavingthe anchor head emplacedand embedded inv themud of the sea bottom. If the anchor head is to beused as the mud-penetrating head on a pile, the shaft extensions. canform that pile, and they would not be withdrawn to the surface. But ifthe anchor head is to hensedas a deademan to anchor down something else,suchas a float,the pipe extensions are so drawn up. But inthis case,around the upper end of the tubular anchor head is provided a band 44with a loop or eye 45 to which can be attached-the wire rope or chain 46leading up to the float.

Now we come to the floating but anchored drill-supporting structureindicated generally by D on which is to be mounted an oil-well drillingrig or other apparatus W. that is to deal with the sea bottom. There arefour floats 50, 51, 52 and 53 which while shown as substantiallyrectangular in shape, can be cylindrical or other suitable shape aslocal circumstances may dictate, but there is a float for each corner ofthe deck and suitably horizontally spaced apart by tying structure 54.Extending-yupwardly through each float is a cylinder 55 having adiameterof say 6 feet for providing a hollow passagewtyupwardlythrough which canrise the upper portion of s piling-56 from its mud anchor H, or anyother suitable .anchor. The floating structure D is formed of a orrupperplatform or deck 57, reinforced such as byz-trusses 58 1ocatedmarginally and otherwise as necessory, and at least a partial lowerplatform or deck 59. On'thenpper'deck 57 is provided a set of winches 60drivenl by motor 60" to each of which winches is secured wire rope or achain 46 leading downwardly catenarily to an anchor head H. Coming backto the construction of eachfloat of which float 51 is an example, andits cylinder 55,- the latter preferably stops at or just above theelevation of the lower deck 59, and also terminating at about that sameheight is a service tube 62 of about 4 feet in diameter to serve as apassageway for a man to get down iBQO'thQFflOflt since it will beequipped with ladder rungs Rj for that purpose. It will also carry apipe 63 from within-the float to a point on upper or main deck 57 forconnection with a pump 65 driven by motor 65 by which water can bepumped out of the float and expelled gh'pipe continuation 64 back to thesea for relieving oat ofsome of its water ballast. Another pump 66,.,.driven by motor 66" is provided exteriorly of the 4 t tube 62 and onthe floats, for supplying water ballast to the float by pumping waterfrom the sea up pipe 67 and down pipe 68 into the float, should it needmore Water ballast than it has at the moment. The ballast-adding pump 66is manually initiated, but the ballast-expelling pump 65 isautomatically controlled in a manner hereinafter described, in additionto being manually operable when desired. In each fioat such as 51 thereis a floatoperated electrical indicating circuit composed of a smallball float 69 within the main float 51, whose vertical fluctuationswill, through rise and fall in an apertured guiding vertical pipe 70 ofa perforated tape and supporting the ball float at its lower end andtaking around a reel at its upper end, operate an electrical circuitconnected to an indicator 71 on the upper deck for indicating the depthof water ballast in the float. The construction and accessories are thesame for each float 50, 51, 52 and 53, but only one such set will bedescribed. The perforated tape type of water-level indicator is made byTelematic Corporation of 2937 North Lincoln Avenue, Chicago 13,Illinois. I

It has been stated that it is important to have the anchored andfloating deck D maintain tension on each of the pilings with which it isassociated. One of the means for accomplishing this is the use in eachcorner of the deck on a piling thereat, of a casing ring and slipindicated generally at S, and shown in more detail in Figs. 12 and 13.It comprises a flanged collar 72 suitably anchored to the deck in aposition encircling the piling and axially within the collar are aplurality of arcuate or curved plates 73, each having an outwardlyextending flange 74 at the top thereof by which the plate is suspendedwithin the collar 72 in a manner whereby the arcuate plates for acylindrical lining are held within the collar 72. Each curved plate 73has a plurality of linearly extending upwardly projecting teeth orridges 75 adapted to bite into the piling if and when the floating decktends to rise with respect to the piling, but which teeth or ridgesslide freely downwardly along the piling if and when the floating decktends to fall with respect to the piling. To serve as a limit to thelowermost elevation to which the floating deck may fall with respect tothe piling, there is provided a casing clamp 76 secured to each pilingat an elevation thereon preferably between the upper and lower decks. Ifthe deck falls far enough to reach that clamp, it will then support thatcorner of the deck directly from its piling.

The automatically controlled motor-operated pump 65 for expelling waterballast from the floats, such as 51, is controlled by a switch 77 in themotor circuit 70 that is energized when the elevation of a corner of thedeck falls with respect to its piling and is de-energized when theelevation of that corner of the deck is restored to its normal positionwith respect to its piling. Any suitable mechanical movement can be usedfor thus operating switch 77, but by way of example, there can be alever 79 fulcrumed at 80 supported from the deck, with its power end 81pivoted at 82 to a piling while its work end 83 carries a yoke 84,adapted on rocking of the lever 79 to move the power end 85 of anotherlever 86 fulcrumed at 87, and whose Work end 88 engages and operates theswitches 77. A spring 89 can be provided to bias the lever 86 againsttoo easy operation. All of this switch operating levered mechanism isindicated generally by the letter L.

As to the operation of embodiments of this invention, since it is firstnecessary to emplace the anchor heads, that and their functioning willbe described initially. Fig. 2 is illustrative of their emplacement froma barge B or other suitable support, from which the anchor head Hsupported from a length of pipe sections such as 25, 27 and 28, suitablysecured together, such as by welding, is descended through the water andforced into the mud M of the seat bottom. The next step is to energizemotor 43 on the barge B to rotate meshing gears 42 and 41 to rotatethrough about 180, shafts 34and 38, with their extensionsrespectively,33 and 37, 32 and 36, and finally 15 and 18 in the anchor head,whereupon the discs 17 on shaft 15 are pivotally moved clockwise outthrough slots 13 until they take their extended weight-supporting andanchoring position as shown in Fig. 5. Similarly, discs 20 on shaft 18are pivotally moved counterclockwise out through slots 14 until theytake their extended and anchoring position as shown in Fig. 5. By havingthe slots 13 and 14 all on one side of the tubular body 12 of the anchorhead H, it seems to remain stronger than if the slots were on alternatesides. Moreover, the slots can be made of minimum length by shaping thediscs the way they are shown to be shaped in Fig. 6, with the tumblehomeat 22 on the fourth quarter Q of the periphery terminating in theshoulder 23. If the anchor head is to be used as a dead-man, after theanchor head has been emplaced, the welded-together pipe sections can beunscrewed from the coupling 24 at the top of the anchor head and removedto the surface, leaving the anchor head in place with its band 44 andloop or eye 45 to which is attached wire rope or chain 46. In sodisconnecting the anchor head, not only does the pipe section 25 becomeunscrewed from the coupling 24, but the shaft 32 comes unfastened fromcoupling 35 and shaft 36 comes unfastened from coupling 40', whereuponthe emplaced anchor head is left in a condition as shown in Fig. 3. Ifthe anchor head is not to be used as a dead-man, but left at the end ofa piling, of course, these removal steps are not carried out.

In Figs. 1 and 8, the floating structure has been shown to be square inplan view, but of course, it could be made of other shapes, if desired,and the same applies to the floats 50, 51, 52 and 53, one of whichsurrounds each piling 56. These floats are held together by suitabletying structures 54, and it is to be understood that the floats areadapted to be used in total submergence whereby they are not subject todamage by surface wave action. Rising through each float and encirclinga piling is a cylinder 55, from the top of which cylinders is supportedthe lower platform or deck 59 from which rise trusses 58 to support theupper or main deck 57 of the floating structure D. Rising from the topof each float, as can be seen from Fig. 10, there is a service tube forproviding access by man along the ladder rungs R into and out from theinterior of the floats. Since it is important to provide means forpumping water from the interior of the float, either to expelwater-ballast therefrom, or to expel water leaking thereinto, such asubmerged pump 65 is fitted in the float while operated by motor 65 ondeck 57, and a pipe 64 conducts the water back to the seal. Waterballastcan be provided for the float by means of pump 66 located exteriorly ofthe float but in submergence, while operated by motor 66 on the deck 57,and pipe 68 conducts water from the sea into the float. The service tubealso contains an apertured vertical pipe 70, in which is supported afloating ball at its lower end by means of a perforated tape T. The ballis adapted to rise and fall with the heights of water in the main floatand as it rises and falls, the tape taking around a reel, rotates thereel to indicate on the indicator 71 on deck 57, the depth of the waterin that particular float.

The floating structure, which is anchored in place by the catenary wireropes or chains 46, secured to the anchor heads H, is floating-supportedfrom the floats 50, 51, 52 and 53, but the floating structure is securedin place over a predetermined spot on the sea bottom by means of thepilings each rising through the cylinders 55 on the floats. Thesepilings are fixedly attached to anchor heads identical to the anchorheads discussed in the second preceding paragraph. But it is alwayspossible that the deck D may not remain level, since one corner thereofmay settle more than another due to more or less water being in thefloat that supports that particular corner. So this invention providesautomatic means for expelling ballast water from a float in the eventthat the 6 corner of the deck it'supports tends to settle or becomedepressed.

However, before describing those means, it should be understood thatsurrounding each piling 56, and supported from the deck 57, is a casingring and slip S (Figures 9, 12 and 13) whose function is to put tensionon the piling if and when the deck tends to rise with respect to thepiling, due to the teeth 75 (on the segments 74 held in the collar 72)biting into the piling when the deck rises, although permittingsubstantially free fall of the deck. If and when the deck settles, thecasing-clamp 76 secured to the piling, 'serves as a limit to thedistance the deck can descend when the upper deck 57 falls enough toengage that clamp (see Figs. 9 and 12).

Referring again to the means for expelling ballast water from thefloats, the ballast-expelling pump 65 for each float has its motor 65 incircuit 78 with a switch 77 (Fig. 11) that energizes the motor when thatcorner of the deck falls, and de-energizes the motor when that cornerrises. This is accomplished, for example, by the arrangement in thatfigure, comprising the lever 79 whose power arm 81 is pivoted at 82 tothe piling and whose work arm 83 operates a second lever 86 that in turneither closes or opens the circuit 78 with its switch 77, remembering,however, that meanwhile, if the corner settles, the extent of suchsettling is limited by the casing clamp 76.

Irrespective of the automatic lever-controlled pump operating means forexpelling ballast water from a float, means are provided for the manualoperation of that pump to remove water from the float, in the event thatthe indicator 71 on the deck shows that the water in the float hasreached too great a depth (or height). The ballast-supplying pump motor66 is manually controlled.

The mud anchor design is capable of other uses than in combination withthe floating structure shown herein, especially in such situationswherein would be advantageous the functioning of the pivoted discs 17and 20 which, when extended, increase the weight-supporting capacity ofthe mud anchors.

As this invention may be embodied in several forms without departingfrom the spirit or essential characteristics thereof, the presentembodiment is therefore illustrative and not restrictive, since thescope of the invention is defined by the appended claims and all changesthat fall within the metes and bounds of the claims or that form theirfunctional as well as conjointly cooperative equivalents, are thereforeintended to be embraced by those claims.

I claim:

1. A mud anchor comprising a hollow tubular shaft open at one end andhaving a mud penetrating portion at its opposite end, said shaft havinga plurality of vertically spaced transverse slots, each slot being of awidth greater than substantially more than one half the circumference ofsaid tubular shaft, a plurality of substantially circular flat metallicplates horizontally and pivotally mounted in staggered relationshipwithin the tubular shaft in substantial alignment with said transverseslots, actuating means for said plates including a plurality ofvertically extending rotatable rods mounted within said tubular shaftand extending through said circular plates and affixed thereto, saidplates being eccentrically mounted thereon such that on rotation of therods said plates will be extended outwardly or retracted, support meansfor said rods secured to the interior wall of said tubular shaft atspaced points therein and through which said rods extend, and meansaflixed to the terminal ends of said rods for imparting rotation to saidrods to extend or retract said flat plates outwardly from said tubularshaft through said transverse slots into engagement with the surroundingmud or inwardly into the surrounding 7 tubular shaftto-allow the,saidqtubular shaft to be recovered from the surrounding mud.

2. A mud anchor as defined in and by claim 1 wherein the diameter ofsaid flat metallic plates is substantially less than the full insidediameter of the, tubular shaft so as to be housed therein and whenextended into engagement with-the surrounding mud present a largebearing area to prevent the anchor from being easily displaced.

References Cited in thefile of this patent UNITED STATES PATENTS 890,765Gilbreth June 16, 1908 Bignell July 8, 1913 Green et a1. Mar. '10, 1931OBrien Dec. 4, 1934 Miller Aug. 17, 1937 Crake Nov. 23, 1943 Wilson July15, 1952 Ross Dec. 16, 1952 McKee Nov. 24, 1953 Mead 'et al. Mar.

